Roof grid types

Variables
const int	Renga::GridTypes::Roof::Undefined = 0
	Undefined.
const int	Renga::GridTypes::Roof::Side = 1
	Side faces of a roof.
const int	Renga::GridTypes::Roof::Bottom = 2
	Bottom faces of a roof.
const int	Renga::GridTypes::Roof::Top = 3
	Top faces of a roof.
const int	Renga::GridTypes::Roof::OpeningSide = 4
	Side faces appearing as a result of insertion of an aperture.
const int	Renga::GridTypes::Roof::OpeningBottom = 5
	Bottom face appearing as a result of insertion of an aperture.
const int	Renga::GridTypes::Roof::OpeningTop = 6
	Top face appearing as a result of insertion of an aperture.
const int	Renga::GridTypes::Roof::Cut = 7
	Faces appearing as a result of cutting a roof by other objects.

Possible grid types for a Roof mesh